Denver ? At least three crude bombs exploded and two others were disarmed Friday at the homes of people who work for an FAA contractor in Grand Junction, prompting evacuation of the air traffic control tower at the city airport, officials said.

No injuries were reported and there were no delays at the airport.

The bombs were placed at homes of people who work for Serco Group Plc., which operates Grand Junction’s air traffic control tower, said Steve Christmas, the company’s vice president for aviation operations. Police asked residents to help them find a former employee they described as a “person of interest.”

Denver controllers handled air traffic for Grand Junction for about an hour until controllers were able to return to the tower there, FAA spokeswoman Laura Brown said. A security sweep was being conducted at Walker Field Airport, said Carrie Harmon, a spokeswoman for the Transportation Security Administration.

The bombs had “no known link to aviation,” Harmon said, and the sweep was conducted “out of an abundance of caution.”